The assistant manager has taken temporary charge of first team proceedings, while boss Paul Martin recovers from a virus.
And the Englishman will call the shots during this weekend's game with Forfar Athletic, as well as the following encounter against lowly Stirling Albion.
Rovers sit second bottom of the Irn-Bru Second Division, with 22 points to their name.
Yet Lumsden's troops have already beaten Forfar twice this season, without conceding a single goal, and the 34-year-old hopes for a similar outcome again.
Lumsden said: "It's going to be a pivotal time in our season. The next two games are absolutely massive.
"We've acquitted ourselves well against the top sides. Now we've got to do the same against the teams around us."
Lumsden began his career with Stirling Albion, before clocking up more than 100 appearances for the Cliftonhill club.
He then spent time with Hamilton and Raith Rovers, eventually making a return to Coatbridge in 2008.
The central defender has worked with Martin ever since, and reckons he is well positioned to ensure the players do not suffer any disruption in the manager's absence.
Lumsden said: "It's not like the players are seeing a new face in front of them, or hearing a new voice. I'm just helping out for now."
Rovers will have to do without the services of suspended Mick O'Byrne.
Elsewhere, Dumbarton will look to keep their fantastic recent record going at home to Stirling Albion.